Suggest The Interaction Between Serotonin And Melatonin

I'm taking 100mg to Sertraline, have been for about 3 years now. For the past year or so I've been taking 5mg of Melatonin every night with the Sertraline an hour or so before bed. A month ago I started having a very uncomfortable 'restless joint' feeling in my knees, elbows and back. I came to find the melatonin was causing this. I discontinued, but now I can't sleep.2 QUESTIONS: What is the interaction between Serotonin and Melatonin?What's a natural sleep aid to replace the melatonin with?